The present invention relates to a display screen device having a display field which can be illuminated by at least one lamp.
Such display screen devices are generally known and are frequently used as notebooks, clocks or handys. The lamp is integrated in the display screen device and connected to the current supply which is in any event present. In this connection, the lamp is either located behind the display field and illuminates it, or it is arranged under a cowling on the edge of the display field and illuminates the field from the side. In order to keep the dimensions of the display screen device within limits, it is endeavored in both cases to arrange the lamp as close as possible to the display field. However, this has the result that, due to the heat given off by the lamp, the display field as well as the display screen device are heated. There is also the disadvantage that the lamp increases the weight and size and, in the event of a portable display screen device, must be taken along by the user even he does not need it.
Since the weight and the size of the display screen device must not exceed a given reasonable amount, the current supply, developed as battery, can be of only limited size. This, in its turn, also leads to a limiting of the possible luminous density which the lamp can produce.
Such display screen devices are subject, as portable units, also to considerable blows, which frequently lead to an early failure in the lamps.
If it is desired to reduce the heating of the display screen device which is effected by a lamp, one can also provide a lamp of the reading-lamp type for illuminating the display field from above. However, this also increases the weight and the volume of the display screen device and leads to undesired reflections.